I have all of this. You need a google account to use GCP and I used my google account which was created with a gmail invite code shortly after gmail was released.

Some things are still using this email. Hey, I'm not perfect. Sometimes I exceed posted speed limits, too.

Edit: I have to choose a tech giant to get a phone app with decent push notifications as far as I can tell (I haven't scoured the earth for this .... yet) The gmail app is pretty good.

Here are options I can recommend: Proton Tuta Apple (iCloud)

All of these withh be your MX with DMARC/SPF. If you use an android cellphone you'll almost certainly need a google account anyhow. The tuta experience is not as advanced as the others, but is servicable and likely offers better security guarantees than the others. You get a lot of bang for your buck from Proton (personal wireguard tunnel vpn included), and apple is apple.